Most consumers have come to expect scented laundry products and to expect that fabrics which have been laundered will also have a pleasing fragrance. It is also desired by consumers for laundered fabrics to maintain the pleasing fragrance over time. Perfume additives may make laundry compositions more aesthetically pleasing to the consumer, and in some cases the perfume imparts a pleasant fragrance to fabrics treated therewith. However, the amount of perfume carry-over from a detergent solution onto a fabric surface is often marginal and does not last long on the fabric surface. In addition, some perfume delivery systems are not stable under alkaline conditions, such as in laundry detergent compositions and detergent solutions. Also, fragrance materials are often very costly. Thus, their inefficient use in detergents and ineffective delivery from detergents to fabric surface usually results in a high cost to both consumers and detergent manufacturers. Industry, therefore, continues to seek more efficient and effective perfume delivery in laundry products.
Acetals and ketals have long been known in perfumery. See Steffen Arctander, "Perfume and Flavor Chemicals," Arctander, N.J., 1969. The majority of these are methyl and ethyl types, and molecular weights may range widely. See, for example, Arctander abstract numbers 6, 11, 210, 651, 689, 1697, 1702, 2480, 2478. However, the known acetals and ketals are generally not desirable for use in laundry products. For 2478, which is phenylacetaldehyde dicitronellyl acetal, molecular weight 414.7, Arctander reports ". . . and it is not exaggerated to say that this acetal is practically abandoned and obsolete in today's perfumery." For 2480, which is phenylacetaldehyde digeranyl acetal, Arctander reports "the title material does not offer substantial advantages or unique odor type and it may be considered of little more than academic interest today." This latter material was still commercially available in 1992 as ROSETAL A (Catalogue, IFF).
Carrier mechanisms for perfume delivery, such as by encapsulation, are also known in the art. See for example, U.S. Pat. No. 5,188,753, issued Feb. 23, 1993.
Early efforts to delay release of perfumes in detergents include the use of certain organometallic compounds, such as titanate or zirconate esters. See U.S. Pat. No. 3,849,326, issued Nov. 19, 1974 and U.S. Pat. No. 3,923,700, issued Dec. 2, 1975. Limited amounts of titanium or zirconium can be useful as catalysts for synthesizing pro-perfume materials.
Personal care compositions, such as deodorant sticks, comprising "body-activated" fragrances are also known. The term apparently refers to the previously known tendency of materials such as acetals derived from perfume alcohols to hydrolyze under acidic pH conditions thereby releasing fragrance. See, for example, U.S. Pat. No. 5,378,468, issued Jan. 3, 1995 and U.S. Pat. No. 3,932,520, issued Jan. 13, 1976.
Potential fragrance materials for use in such personal care compositions include particular acetals and ketals, exemplified by propylene glycol vanillin acetal. The materials exemplified apparently are rather hydrophilic short chain alcohol or diol derivatives of fragrance aldehydes and upon hydrolysis, deliver one mole of the aldehyde per mole of the potential fragrance material. This development is designed to be incorporated with a personal care product vehicle, resulting in clear deodorant sticks and the like and the compositions containing the potential fragrance materials are applied directly to the substrate (i.e. skin); therefore, the deposition problems resulting from the dilution, rinsing, etc., associated with the laundry process are not at issue.
Factors affecting substantivity of fragrance materials on fabrics are discussed in Estcher et al. JAOCS 71 p. 31-40 (1994).
Laundry detergents are used in dilute aqueous form and contain numerous detergent adjuncts such as synthetic detergents, builders, enzymes and the like which are capable of micellizing, or solubilizing the pro-fragrance. Further, the laundry process includes rinsing, and sometimes drying with tumbling machines after washing. The rinsing tends to remove the useful pro-fragrance material deposited. The tumble-drying further exacerbates the problem of delivering adequate residual fragrance to textile fabric surfaces.
The pro-fragrance compounds of the present invention can be used for a variety of products wherein the conventional fragrances are used. These are, for example, such as shampoos, conditioners, detergent hard surface cleaner, deodorants, cat litter, and the like.
Based on the foregoing, there is a need for a pro-fragrance compound with improved dispersability in aqueous solutions. Especially, pro-fragrance compound used for detergent composition further can be enhanced deposition on fabric surfaces in the wash solution, and enhanced retention on the washed surface during rinsing. None of the existing art provides all of the advantages and benefits of the present invention.